Each box to be legibly marked with the name of the manufacturer or supplier&comma; the alloy designation of material&comma;condition&comma;dimensions and weight

6&period;3

Shipping tools

Ship goods by van to departune port then by sea to desitination port

6&period;4

Quantity variation

±10&percnt; variation with order quantity shall be acceptable

7&period; Brief of extrusion

Extrusion is a process used to create objects of a fixed cross-sectional profile&period; A material is pushed through a die of the desired cross-section&period; The two main advantages of this process over other manufacturing processes are its ability to create very complex cross-sections&comma; and to work materials that are brittle&comma; because the material only encounters compressive and shear stresses&period; It also forms parts with an excellent surface finish&period;&lsqb;1&rbrack;

Drawing is a similar process&comma; which uses the tensile strength of the material to pull it through the die&period; This limits the amount of change which can be performed in one step&comma; so it is limited to simpler shapes&comma; and multiple stages are usually needed&period; Drawing is the main way to produce wire&period; Metal bar and tube are also often drawn&period;

Extrusion may be continuous &lpar;theoretically producing indefinitely long material&rpar; or semi-continuous &lpar;producing many pieces&rpar;&period; The extrusion process can be done with the material hot or cold&period; Commonly extruded materials include metals&comma; polymers&comma; ceramics&comma; concrete&comma; play dough&comma; and foodstuffs&period; The products of extrusion are generally called "extrudates"&period;

Hollow cavities within extruded material cannot be produced using a simple flat extrusion die&comma; because there would be no way to support the center barrier of the die&period; Instead&comma; the die assumes the shape of a block with depth&comma; beginning first with a shape profile that supports the center section&period; The die shape then internally changes along its length into the final shape&comma; with the suspended center pieces supported from the back of the die&period; The material flows around the supports and fuses together to create the desired closed shape&period;

The extrusion process in metals may also increase the strength of the material&period;

Process

The process begins by heating the stock material &lpar;for hot or warm extrusion&rpar;&period; It is then loaded into the container in the press&period; A dummy block is placed behind it where the ram then presses on the material to push it out of the die&period; Afterward the extrusion is stretched in order to straighten it&period; If better properties are required then it may be heat treated or cold worked&period;&lsqb;2&rbrack;

The extrusion ratio is defined as the starting cross-sectional area divided by the cross-sectional area of the final extrusion&period; One of the main advantages of the extrusion process is that this ratio can be very large while still producing quality parts&period;